The present invention relates to a device for transporting recording media to a specific position in the transport portion of an image forming apparatus such as that of laser printers, photocopiers and other printing devices.
In the image forming devices of printers and the like, the recording medium is transported in a transport path contained in the image forming device so as to form a desired image on said recording medium while being transported therein. When a sheet-type recording medium is used, the transport path may be formed using a flat guide member so as to counteract the tendency of the sheet to curl.
However, as rolled recording media is unrolled it is cut to a specified length for image formation within the image forming device, but it has a tendency to rewind after being cut into a sheet due to the effect of its former rolled condition. This tendency is particularly great at the corners of the sheet, with greater curling occurring with longer and wider sheets. Therefore, a flat guide is provided in the sheet transport path to prevent curling and guide the sheet in image formation devices wherein the rolled recording media is cut for the image formation process.
In laser printers, for example, paper coated with a photosensitive agent or photosensitive film may be used as the recording media which are configured so as to form a sheet roll that is loaded into a magazine within the printer. During printer operation, the media are continuously output from the magazine, cut to a specified length by a cutter, and transported to the secondary scanning portion where an image is printed thereon. At low temperatures, the media coated with a photosensitive agent will start to curl regardless of curling tendency related to its rolled configuration prior to cutting. Accordingly, curling cannot be controlled when, after cutting, the recording medium is transported while being partially pressed by a flat guide, rather the degree of curling at the corners of the sheet then becomes more pronounced. When more than one size of recording medium is transported in the same printer, the positioning of the corners of the different sized sheets is different and preventing sheet jamming can be difficult. It is therefore preferred that laser printers and other image forming devices using rolled recording media that are cut and then transported use medium which can be transported in the device without curling.